SiteFusion allows object-oriented PHP applications to operate as
OS-native applications through a XULRunner-based thin client. The client
connects to the SiteFusion daemon through an ordinary Web server, and
applications run in separate continuous processes. Two-way communication
is enabled, without the need for additional Web server configurations.
The implementation of the XUL framework in a PHP class structure
includes an implementation of the Mozilla tree view optimized for very
large trees, supporting drag-and-drop, editable cells, and sorting.

SEMS is a media and application server for SIP based VoIP services. It shows good performance doing basic services like announcements and conference for combination with external application servers. Thanks to its easy-to-use and flexible application development framework and back-to-back user agent support, application logic and media serving can be combined in the same process. Basic applications like announcement, pre-call announcement, RBT, conference, voicemail, mailbox, and lots of example applications are available. Scripting can be done in Python and a simple state machine description language. Support All commonly used free codecs (including g711, gsm, iLBC, speex, adpcm, and l16) are supported. Other features include wideband, ZRTP encryption, a SIP registrar client, an XMLRPC server/client, and a DIAMETER client.

WAWAS is a full PHP application server.
The main server core listens to any IP/port and passes data to any mounted protocol on the listener. Implemented protocols are HTTP1.1/1.0, Comet, Telnet, DNS, mail, and FTP. Each protocol runs modules that build response data based on the requests. Memory object persistence allows data and caches to be shared across protocols or time. All configuration uses XML. It can be launched as a daemon, with or without forked workers, and is nearly as fast as Apache in preliminary tests.

Zato is an Enterprise Service Bus (ESB) and app server written by pragmatists for pragmatists. It provides an HA load-balancer, hot-deployment, and hot-reconfiguration almost everywhere (forget server restarts). It has a browser-based GUI, CLI, and API (forget XML configuration). It supports many protocols, industry standards, and data formats, including HTTP, JSON, SOAP, REST, AMQP, JMS WebSphere MQ, ZeroMQ, Redis, SQL, and FTP.

appserver.io is a multithreaded application server for PHP. Applications can be installed using drag and drop. It has outstanding performance, with benchmarking on nginx showing that it is about 50% faster than nginx alone (based on a standard Magento installation) with no additional tweaks.